A central processing complex (CPC), offered by International Business Machines Corporation, is capable of concurrently executing a plurality of control zones. For example, a central processing complex 100 (FIG. 1a) executes one or more operating system zones 102 and a coupling facility zone 104. Each operating system zone 102 executes an operating system, such as for instance, the OS/390 (or Multiple Virtual Storage (MVS)) operating system, offered by International Business Machines Corporation; and coupling facility zone 104 executes coupling facility control code used in aiding the clustering of zones and/or multiple central processing complexes.
Previously, when an operating system zone and a coupling facility zone within a single central processing complex wished to communicate with each other, there were two options available, as shown in FIGS. 1a-1b. In FIGS. 1a, an operating system zone 102 communicated with a coupling facility zone 104 via a pair of I/O channels 106, 108, interconnected by an external cable 110. In particular, the data is passed from the main memory of the operating system zone to one of the I/O channels of the pair. Thereafter, it is moved from the one I/O channel to its corresponding I/O channel pair, and then to the main memory of the coupling facility zone. Data is similarly moved from the coupling facility zone to an operating system zone. The requirement of a pair of I/O channels, however, disadvantageously adds cost to CPC 100. Further, the I/O channels typically have limited bandwidth.
The second option is described with reference to FIG. 1b. In FIG. 1b, data is moved between an operating system zone 102 and coupling facility zone 104 via one or more processors 120, which execute a coupling facility zone program to move the data. Specifically, special processor instructions are made available to the coupling facility zone that allow its processors to move data between its main memory and main memory of the operating system zone. This internal virtual I/O channel eliminates the need for normal I/O channels, but is costly in that it requires processor resources (i.e., processor instructions) to perform the data movement.
Thus, although various options are currently available for moving data between operating system and coupling facility zones, a need still exists for an improved capability for communicating between zones of a central processing complex. In particular, a need exists for a data movement capability that moves data between the various zones, and is less costly and has better bandwidth than the previous techniques.